Sample vial plug



FIG. 1 is a top plan view of a sample vial plug showing my new design;

FIG. 2 is a top perspective view thereof;

FIG. 3 is a bottom plan view thereof; and

FIG. 4 is a side elevational view thereof, the undisclosed sides being identical thereto. 

The ornamental design for a sample vial plug, as shown and described. 